The present invention relates to a cartridge mixer for mixing two fluent materials and particularly to such a mixer wherein the two fluent materials are kept separated in the cartridge body prior to their mixing and subsequent dispensing.
The fluent materials to be mixed with the mixer according to the invention are of unlimited variety. Their characteristic is that they are not sufficiently liquid that they can be thoroughly mixed by agitation of the mixer body, but they must instead be assisted by a mixing apparatus that moves through the fluent materials to mix them. Furthermore, the two materials typically react in some manner when they are mixed, and it is desirable therefore to keep the materials separated until they are mixed. For example, these mixers may be used for mixing two quite viscous, fluent materials which react to form a foam that hardens shortly after it is mixed. In particular, the mixer can be used to mix a base material and a catalyst to produce sealant compound. In the example wherein the fluent materials are mixed and the foam begins to form, the volume occupied by the combined, reacted materials is larger than that occupied by its previously separated components. The foam must be dispensed because as the foam further expands, it would occupy still more volume and furthermore, as the foam gradually hardens, it would make subsequent dispensing and use of the foam impossible.
Various mixers for mixing two such fluent materials are known. One type of mixer shown in U.S. Pat. No. 3,144,966 includes two compartments or chambers in a single body, and the chambers are separated by a breakable separator. A plunger supports a mixer which is movable through the body to mix the fluent materials. In a known modification of the patented disclosure, the separated components are held in two chambers within the body, and the mixer is moved through both chambers of the body, first to pierce and break the separator and thereafter to be moved back and forth to mix the materials. Once the fluent materials have been mixed, the plunger is operated to move the product dispensing means to dispense the product through the exit from the body.
The cartridge is typically a single use, disposable unit and its design is preferably simple and inexpensive.